436 CHEMICAL DUALITIES OF THE CUTICLE. 



or is merely an inanimate unorganized concrete. No decisive 

 argument have been adduced in favor of its vitality ; and it 

 has already been stated, that neither nerves nor vessels can be 

 demonstrated in it. 



It appears particularly calculated for protecting the skin 

 which it covers ; for it is insoluble in water, and resists the 

 action of several powerful Chemical agents. Thus, it is not 

 affected by immersion for a considerable time m the sulphuric 

 and muriatic acids ; although the nitric acid acts upon it. 



It resists for a short time, but is at length dissolved, by the 

 pure fixed alkalies, and by lime. 



It is supposed by the chemists to consist of albumen, in a 

 peculiar state of modification. 



Malpighi, was the first to discover, by the use of the 

 microscope, an intervening substance between the cuticular 

 covering, and the cutis vera, which he called the rete mucosum 

 or corpus reticulare. This he considered the seat of coloration 

 in the negro, and asserted the cuticle to be alike in all varieties 

 of the human race that is, colorless. For a long period his 

 researches formed the basis of all the systematic treatises upon 

 the skin, and it is only within a recent period, as has before 

 been observed, that the study of the subject has been resumed. 

 The cuticle of the black is now generally admitted to be of 

 an ashy color.* And Flourensf has shown, that the reticular 

 appearance of the rete mucosum is entirely an adventitious 

 circumstance. Malpighi first discovered his rete mucosum on 



* Breschet has asserted that the color of the skin in different animals is 

 dependent upon the form of the scales of the epidermis, by which the light is 

 reflected. 



Fig. 115. The larger cut represents, after this observer, the 



scales of the epidermic or corneous matter of a 

 white man, diluted with water, and highly magni- 

 fied, in which are seen fragments of the sudoriferous 

 canals and inhalent vessels. The scales all have a 

 trapezoidal or lozenge shape. The smaller cut, 

 represents a single scale from the skin of a whale, 

 highly magnified. It is black at its summit, and 

 whitish at its pedicle of insertion. The skin of the whale is black, and these 

 writers assert, that in all animals with black skins, including negroes, the scales 

 of the epidermis, appear under the microscope of this shape or spatulate. P. 

 f Annales des sciences naturelles, 1837. 



